EXPLANATION OF THE SEA-SERPENT MAGNETIC STRUCTURE OF SUNSPOT PENUMBRAE

Journal Article · Sun Jun 20 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/716/2/L181· OSTI ID:21451073

Kitiashvili, I N ^[1]; Bellot Rubio, L R ^[2]; Kosovichev, A G ^[3]; Mansour, N N; Wray, A A ^[4]

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1. Center for Turbulence Research, Stanford University, Stanford, CA 94305 (United States)
2. Instituto de Astrofisica de AndalucIa (CSIC), Apdo. de Correos 3004, E-18080 Granada (Spain)
3. NORDITA, Department of Astronomy, AlbaNova University Center, SE 10691 Stockholm (Sweden)
4. NASA Ames Research Center, Moffett Field, Mountain View, CA 94040 (United States)

Recent spectro-polarimetric observations of a sunspot showed the formation of bipolar magnetic patches in the mid-penumbra and their propagation toward the outer penumbral boundary. The observations were interpreted as being caused by sea-serpent magnetic fields near the solar surface. In this Letter, we develop a three-dimensional radiative MHD numerical model to explain the sea-serpent structure and the wave-like behavior of the penumbral magnetic field lines. The simulations reproduce the observed behavior, suggesting that the sea-serpent phenomenon is a consequence of magnetoconvection in a strongly inclined magnetic field. It involves several physical processes: filamentary structurization, high-speed overturning convective motions in strong, almost horizontal magnetic fields with partially frozen field lines, and traveling convective waves. The results demonstrate a correlation of the bipolar magnetic patches with high-speed Evershed downflows in the penumbra. This is the first time that a three-dimensional numerical model of the penumbra results in downward-directed magnetic fields, an essential ingredient of sunspot penumbrae that has eluded explanation until now.

• OSTI ID: 21451073
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 716; ISSN 2041-8205
• Country of Publication: United States
• Language: English

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